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Please Solve RD Sharma Class 12 Chapter Function Exercise 2.4 Question 15 Maths Textbook Solution.

Answers (1)

Answer:

                f^{-1}\left ( 43 \right )2,f^{-1}\left ( 163 \right )=4

Given:

                f:N\rightarrow N is a function defined as f\left ( x \right )=9x^{2}+6x-5.

Hint:

The function should be an identity function.

Solution:

Let          y=f\left ( x \right )=9x^{2}+6x-5

                y=9x^{2}+6x+1-1-5 

                y=\left (9x^{2}+6x+1 \right )-6

                y=\left ( 3x+1 \right )^{2}-6

                y+6=\left ( 3x+1 \right )^{2}

                \sqrt{y+6}=\left ( 3x+1 \right )                                                                                                                          

                \sqrt{y+6}-1=3x

               

                   (Let )

Now,    

                               

                               

               =y+6-6

               

                                 Identity function.

               

                               

                               

                               

                               

                                 Identity function

Since andare identity functions.

Thus is invertible.

So,         

Now,    

               

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